JP2003217965A - Method of manufacturing stacked ceramic electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a method of manufacturing stacked ceramic electronic components which can control the formation of ball of internal electrode, without generation of fault in the structure due to the oxidation of the Ni electrode used as the internal electrode. <P>SOLUTION: The stacked ceramic electronic component 10 includes a ceramic element 12, consisting of a ceramic layer 14 and a Ni internal electrode 16. At the opposing end face of the ceramic element 12, external electrodes 18, 20 connected to the internal electrode 16 are formed. At manufacturing of the ceramic element 12, an electronic paste including Ni is coated on a ceramic green sheet, the ceramic green sheets are laminated and these are baked after cutting process. In this case, a partial pressure P1 of oxygen, before starting the sintering of the internal electrode, is set to a range with log P1<-15. Moreover, when the partial pressure of oxygen, after starting the sintering of the internal electrode is defined as P2 and the equilibrium partial pressure of oxygen of 2Ni+O<SB>2</SB>=2NiO is defined as P3, these partial pressures are to be set to a range of 1.1×log(P3)≤log(P2)≤log(P3). <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer ceramic electronic component, and more particularly, for example, a multilayer ceramic capacitor in which an internal electrode is formed using a Ni electrode material. The present invention relates to a method for manufacturing a ceramic electronic component. For example, in a multilayer ceramic capacitor using Ni as an internal electrode, an internal electrode pattern is formed on a ceramic green sheet using an electrode paste containing Ni, and the ceramic green sheet is laminated. Thus, a laminated body is formed. This laminated body is cut to form a chip-like laminated body in which adjacent internal electrode patterns are alternately exposed on the opposing end faces. By firing the laminated body thus cut, a ceramic body in which internal electrodes are formed in the ceramic layer is obtained. Then, an external electrode is formed on the end face of the ceramic body from which the internal electrode is exposed, and the internal electrode and the external electrode are connected to produce a multilayer ceramic capacitor. Thus, when firing the cut laminate, it is necessary to control the oxygen partial pressure in the firing furnace so that Ni in the internal electrode pattern is not oxidized. If the oxygen partial pressure in the firing furnace is outside a certain range,
The internal electrodes are oxidized to cause structural defects, or the ceramic body is deteriorated in sinterability and the insulation resistance is deteriorated. In order to avoid such problems, there is a method of defining the oxygen partial pressure in the firing process of the laminated body within a certain range as disclosed in, for example, Japanese Patent Laid-Open No. 6-196352. In the method disclosed in JP-A-6-196352, a degreasing zone, a sintering zone,
This is divided into oxygen defect replenishment zones, and the oxygen partial pressure is controlled within a predetermined range in each zone. SUMMARY OF THE INVENTION Problems to be Solved by the Invention
The method disclosed in Japanese Patent No. 2 divides the sintering temperature of the laminate of ceramic green sheets into a plurality of zones, and controls the oxygen partial pressure in each zone. However, as the ceramic layer becomes thinner, the particle size of the Ni particles contained in the internal electrode material becomes smaller, and when fired in the atmosphere disclosed in Japanese Patent Laid-Open No. 6-196352, the internal electrode becomes balled. . For this reason, a problem has arisen in that the internal electrode that has been turned into a ball penetrates the ceramic layer and the insulation resistance deteriorates. Further, it was found that when the firing atmosphere is set to an atmosphere that suppresses the internal electrode from turning into a ball, structural defects accompanying the oxidation of the internal electrode occur. SUMMARY OF THE INVENTION Therefore, a main object of the present invention is to provide a method for manufacturing a multilayer ceramic electronic component capable of suppressing internalization of internal electrodes without causing structural defects due to oxidation of Ni electrodes used as internal electrodes. Is to provide. The present invention is a method of manufacturing a multilayer ceramic electronic component in which a Ni electrode is formed as an internal electrode, wherein the internal electrode pattern is formed using an electrode material containing Ni. Including a step of preparing a laminated body in which ceramic green sheets are laminated, and a step of firing the laminated body, wherein an oxygen partial pressure P1 (atm) of a firing atmosphere before starting sintering of the internal electrode pattern is logP1 <-15. And the oxygen partial pressure P2 (atm) of the firing atmosphere after the sintering of the internal electrode pattern is 2Ni + O ₂ ⇔2NiO
When the equilibrium partial pressure of oxygen is P3 (atm), 1.1 ×
logP3 ≦ logP2 ≦ logP3 (however, log
P1 <0, logP2 <0, logP3 <0). By controlling the partial pressure of oxygen in the firing atmosphere before and after the start of sintering of the internal electrode pattern containing Ni, the internal electrode can be prevented from spheroidizing, and the internal electrode It is possible to prevent the occurrence of structural defects associated with the oxidation of the. Before the sintering of the internal electrode, the Ni particles have a large particle size and high activity.
Therefore, when the oxygen partial pressure in the firing atmosphere increases, the internal electrode starts to oxidize and induce structural defects. Therefore, it is preferable that the oxygen partial pressure before the start of sintering of the internal electrode is low. Moreover, if the sintering of the internal electrode proceeds to some extent and the surface area of the Ni particles is small, structural defects do not occur even if the oxygen partial pressure is increased to some extent, and conversely, if the oxygen partial pressure is too low, It will be spheroidized during sintering. Therefore, after starting the sintering of the internal electrode, the laminate is fired in an atmosphere having a higher oxygen partial pressure than before the start of sintering. The above object, other objects, features, and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings. DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an illustrative view showing an example of a multilayer ceramic capacitor produced by a method for producing a ceramic electronic component according to the present invention. The multilayer ceramic capacitor 10 includes a ceramic body 12. The ceramic body 12 includes a plurality of ceramic layers 14 and internal electrodes 16.
Are alternately stacked. Adjacent internal electrodes 16 are alternately exposed on the opposing end faces of the ceramic body 12, and these internal electrodes 1 are exposed.
External electrodes 18 and 20 are formed so as to be connected to 6. The ceramic layer 14 is made of a dielectric ceramic, and the internal electrode 16 is made of Ni. The external electrodes 18 and 20 are formed of, for example, a Cu baking electrode layer, a Ni plating layer, a Sn plating layer, or the like. When the multilayer ceramic capacitor 10 is manufactured, a ceramic green sheet formed of a dielectric material is prepared. An internal electrode pattern is formed on the ceramic green sheet using an electrode paste containing Ni. A plurality of ceramic green sheets on which internal electrode patterns are formed are stacked, and further, ceramic green sheets on which no electrode patterns are formed are stacked. The laminated body obtained in this way is pressure-bonded and cut into chips in order to produce the ceramic body 12. The laminated body cut into chips is fired to form a ceramic body 12 composed of a ceramic layer 14 and internal electrodes 16. The laminate is fired in a mixed gas atmosphere such as H ₂ gas, N ₂ gas, CO gas, and CO ₂ gas. At this time, the oxygen partial pressure of the firing atmosphere is adjusted in the temperature range before the start of sintering of the internal electrode pattern formed of the electrode paste containing Ni and the temperature range after the start of sintering. Prior to the start of internal electrode sintering, the oxygen partial pressure P1 (atm) of the firing atmosphere in the firing furnace is log P1.
<-15 is adjusted. In addition, after starting the internal electrode sintering, the oxygen partial pressure P2 (atm) of the firing atmosphere in the firing furnace is 1.1 × log when the equilibrium oxygen partial pressure of 2Ni + O ₂ ⇔2NiO is P3 (atm).
It is adjusted to be within the range of P3 ≦ logP2 ≦ logP3. Where logP1 <0, logP2 <0,
logP3 <0. The ceramic body 1 with the internal electrode 16 exposed.
External electrodes 18 and 20 are formed on the two end faces. In order to form the external electrodes 18 and 20, an electrode paste containing Ag, Cu and a glass component is applied to the end face of the ceramic body 12 and baked. External electrodes 18 and 20 are formed by forming a Ni plating layer, a Sn plating layer, and the like on the baked electrode thus obtained. When the laminate is fired, the Ni particles have a large surface area and high activity before the internal electrode sintering is started. Therefore, when the oxygen partial pressure in the firing atmosphere in the firing furnace is high, the internal electrodes begin to oxidize and induce structural defects.
On the other hand, by adjusting the oxygen partial pressure P1 (atm) of the firing atmosphere before starting the internal electrode sintering so as to be in the range of logP1 <−15, the internal electrode is prevented from being oxidized and the structural defect is It can be prevented from occurring. Furthermore, after the internal electrode sintering starts,
The sintering of the internal electrode proceeds to some extent, the surface area of the Ni particles is reduced, and no structural defects occur even if the oxygen partial pressure is increased to some extent. Conversely, if the oxygen partial pressure is too low in this temperature range, the internal electrode will bend during sintering,
The insulation resistance of the multilayer ceramic capacitor 10 deteriorates through the ceramic layer 14. On the other hand, the oxygen partial pressure P2 (atm) of the firing atmosphere in the firing furnace is 2N.
When the equilibrium oxygen partial pressure of i + O _{2 、} 2NiO is P3 (atm), 1.1 × logP3 ≦ logP2 ≦ logP
By adjusting so as to be within the range of 3, it is possible to prevent the internal electrode from becoming ball. Therefore, it is possible to prevent the ceramic layer 14 from being broken due to the internal electrodes, and the insulation resistance of the multilayer ceramic capacitor 10 can be prevented from deteriorating. Thus, structural defects of the internal electrode 16 can be prevented by adjusting the oxygen partial pressure in the firing atmosphere according to the temperature range before the start of internal electrode sintering and the temperature range after the start of sintering. The internal electrode 1
6 can be prevented from becoming dull, and insulation deterioration of the multilayer ceramic capacitor can be prevented. EXAMPLE 1 A binder (polyvinyl butyral), a plasticizer (dioctyl phthalate), and a toluene / equinene mixed solution are added to a dielectric ceramic material and kneaded in a ball mill for several hours to several tens of hours. Thus, a ceramic slurry was formed. The resulting ceramic slurry is formed into a sheet with a predetermined thickness by the doctor blade method,
A ceramic green sheet was obtained. After printing the electrode paste containing Ni particles on the obtained ceramic green sheet and laminating the ceramic green sheets, 3.2
Cut to a size of × 2.5 mm. The cut laminate is heated at 240 ° C. to 2 ° C. in the atmosphere.
Degreased at 80 ° C. The degreased laminates were arranged on an alumina bowl and fired in a closed batch furnace. The firing atmosphere at this time is a mixed gas atmosphere such as H ₂ gas, N ₂ gas, CO gas, CO ₂ gas, and the oxygen partial pressure at each temperature is
As shown in Table 1. The rate of temperature increase during firing is from 1 to 2 ° C./min from room temperature to the maximum temperature, and the maximum temperature (1
250 degreeC-1350 degreeC), it hold | maintained for 1 to 3 hours, and it cooled to normal temperature at 3-4 degreeC / min after that. 500 ceramic bodies thus obtained were extracted, and the presence or absence of structural defects in the internal electrodes was confirmed with a 20-fold magnifier. Also, after applying and baking the Ag external electrode to the ceramic body, 200 pieces were extracted,
A voltage 10 times the rated voltage was applied to count the number of short-circuit defects. The results are shown in Table 1.
The internal electrode was subjected to TMA analysis (thermomechanical analysis) under an inert atmosphere, and the electrode contraction start temperature and end temperature were specified. [Table 1] In this embodiment, the electrode paste for internal electrodes starts shrinking from 800 ° C.
Condition 1 shows the case where the firing is continued while maintaining the same oxygen partial pressure as before the sintering start even after the internal electrode sintering start, as indicated by the underline in Table 1. In the case of this condition 1, 100% withstand pressure failure occurred in the sample after firing. This is because the internal electrode spheroidizes when sintered and penetrates the ceramic layer. 2Ni + O ₂ ⇔2N even after internal electrode sintering
If the value is kept larger than the equilibrium oxygen partial pressure of iO on the reduction side, the NiO ratio is extremely reduced, and it is almost composed only of metallic Ni. In that case, (metal Ni + metal N
The neck growth associated with the sintering of i) is (metal Ni + Ni
O) or (NiO + NiO) occurs more rapidly. In this way, the internal electrode becomes spheroidized as the sintering progresses. However, in this temperature range, the ceramic layer has not yet started sintering, and the binder is in a temperature range where it is sufficiently decomposed. The strength of the layer is weakened. As a result, the ceramic layer is broken by the internal electrodes that are turned into a ball, and the adjacent internal electrodes are short-circuited, resulting in a breakdown voltage failure. On the other hand, in condition 2 and condition 3,
By increasing the oxygen partial pressure after the start of the internal electrode sintering from before the start of the sintering, the internal electrode did not become spheroidized and no pressure resistance failure was observed. Thus, by greatly changing the atmosphere before and after the start of the sintering of the Ni electrode used as the internal electrode, it was possible to prevent the internal electrode from spheroidizing and greatly reduce the breakdown voltage failure rate. Example 2 In the same manner as in Example 1, ceramic green sheets coated with an electrode paste were laminated and cut to obtain a chip-like laminate. TMA that internal electrode shrinkage starts at 800 ° C as a preliminary evaluation.
In the range from 700 ° C. before the start of shrinkage to 1100 ° C. where the shrinkage is completed after confirmation by analysis, as shown in Table 2, 100
Experiments were carried out by adjusting the oxygen partial pressure in the furnace every ° C. Thus, the firing atmosphere was adjusted, and the breakdown voltage failure rate and the short-circuit failure rate were examined in the same manner as in Example 1. The results are shown in Table 2. For reference, the equilibrium oxygen partial pressure logP3 in each temperature range and the value of 1.1 × logP3, which is the lower limit of the oxygen partial pressure of the present invention, are also shown in Table 2. [Table 2] As can be seen from Table 2, when the oxygen partial pressure at 700 ° C. is P1 (atm), as shown by the underline in Table 2, if the value of log P1 is −15 or more, the multilayer ceramic capacitor has a poor withstand voltage. Was recognized. This is because, in the stage before the start of internal electrode sintering, the surface area of Ni particles is large and the activity is high, so that oxidation starts when a partial oxygen partial pressure in the furnace increases even slightly and induces structural defects. Also, 800 ° C. after the start of internal electrode sintering.
The oxygen partial pressure at ˜1100 ° C. is P2 (atm), where the equilibrium oxygen partial pressure of 2Ni + O ₂ ⇔2NiO at each temperature is P3 (atm), 1.1 × log P3 ≦ lo
When it was in the range of gP2 ≦ logP3, a multilayer ceramic capacitor free from defects could be obtained. On the other hand, as indicated by the underline in Table 2, logP2 is 1.1 ×
When it was lower than log P3, a short circuit defect was observed in the multilayer ceramic capacitor. This is because, if the Ni electrode is sintered to some extent and the surface area is small, structural defects do not occur even if the oxygen partial pressure is increased to some extent, and conversely, the oxygen partial pressure is too low in this temperature range. This is because the internal electrode becomes spheroidized during the sintering and breaks through the ceramic layer. According to the present invention, Ni is used as the internal electrode.
When manufacturing a multilayer ceramic electronic component in which an electrode is used, it is possible to prevent the Ni electrode from being oxidized and causing structural defects. Furthermore, when sintering the internal electrode,
It is possible to prevent spheroidization of the Ni electrode, and it is possible to prevent breakage of the ceramic layer due to the spheroidized Ni electrode. Therefore, for example, when a multilayer ceramic capacitor is manufactured using the manufacturing method of the present invention, it is possible to obtain a multilayer ceramic capacitor having a sufficient breakdown voltage and having no short-circuit defect.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an illustrative view showing one example of a multilayer ceramic capacitor produced by the production method of the present invention. [Description of Symbols] 10 Multilayer Ceramic Capacitor 12 Ceramic Body 14 Ceramic Layer 16 Internal Electrode 18 External Electrode 20 External Electrode

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5E001 AB03 AC09 AH08 AH09                 5E082 AB03 BC38 EE04 EE23 EE35                       FG06 FG26 FG54 LL01 LL02                       PP07

Claims (1)

What is claimed is: 1. A method of manufacturing a multilayer ceramic electronic component having an Ni electrode formed as an internal electrode, wherein a ceramic green sheet having an internal electrode pattern formed by using an electrode material containing Ni is stacked A step of preparing the laminated body and a step of firing the laminated body, wherein the oxygen partial pressure P1 (atm) of the firing atmosphere before the sintering of the internal electrode pattern is in a range of logP1 <−15 And the oxygen partial pressure P2 (atm) of the firing atmosphere after the sintering of the internal electrode pattern is 2Ni + O ₂ Ｎｉ2Ni
When the equilibrium oxygen partial pressure of O is P3 (atm), 1.1
× logP3 ≦ logP2 ≦ logP3 (however, lo
A method for producing a multilayer ceramic electronic component, wherein gP1 <0, logP2 <0, logP3 <0).